Qi:  ''^1 


/-A^t)    •  o      i^O 


JUN  15  190 
O.E..-.DS  CONNECTICUT  n^. 


ilGRICULTURAl  EXPERIMEIT  STATION 


NE\\r     HAVEN,    CONN. 


BULLETIN   150,  JUNE,   1905. 


The  Selection  of  Tobacco  Seed  Plants. 


CONTENTS. 

Page. 

Possibility  of  Improving  the  Quality  of  Tobacco 3 

Lack  of  Uniformity  of  Plants  in  the  Average  Tobacco  Crop 5 

Self-Fertilization  and  Cross-Fertilization  of  Tobacco 8 

Advantages  of  Using  Seed  from  Self-Fertilized  Flowers 9 

Method  of  Selecting  Plants  and  Securing  Self-Fertilization 12 


The  Bulletins  of  this  Station  are  mailed  free  to  citizens  of  Con- 
necticut who  apply  for  them,  and  to  others  as  far  as  the  editions 
permit. 


CONNECTICUT  A&EICULTDRAL  EIPERIMENT  STATION. 

o:f':fice]i?,s  -A-dstid    st.a.:f:f_ 

BOARD   OF   CONTROL. 
His  Excellency,  Henry  Roberts^  Ex  officio,  President. 

Prof.  W.  O.  Atwater  Middletown. 

Prof.  W.  H.  Brewer,  Secretary New  Haven. 

B.  W.  Collins  Meriden. 

T.  S.  Gold West  Cornwall. 

Edwin  Hoyt   New  Canaan. 

J.  H.  Webb Hamden. 

E.  H.  JenkinSj  Director  and  Treasurer New  Haven. 


STATION    STAFF. 

Chemists. 

Analytical  Laboratory. 

A.  L.  WiNTON,  Ph.D.,  Chemist  in  charge. 

E.  Monroe  Bailey,  Ph.B.  I.  A.  Andrews,  Ph.B. 

Kate  G.  Barber,  B.S. 

Laboratory  for  the  Study  of  Proteids. 
T.  B.  Osborne,  Ph.D.,  Chemist  in  charge.  I.  F.  Harris,  M.S. 

Botanist. 
G.  P.  Clinton,  S.D. 

Entomologist. 
W.  E.  Britton,  Ph.D. 

Assistant  to  the  Entomologist. 
B.  H.  Walden,  B.Agr. 

Forester. 
Austin  F.  Hawes,  M.F. 

Grass  Gardener. 
James  B.  Olcott^  South  Manchester. 

Stenographers  and  Clerks. 

Miss  V.  E.  Cole. 
Miss  L.  M.  Brautlecht. 

In  charge  of  Buildings  and  Grounds. 
William  Veitch. 

Laboratory  Helper. 
Hugo  Lange. 

Sampling  Agent. 
V.  L.  Churchill,  New  Haven. 


The  Selection  of  Tobacco  Seed  Plants.' 

By  a.  D.  Shamel, 

Of  the  Bureau  of  Plant  Industry,  U.  S.  Department  of  Agriculture,  in 

Cooperation  with  the  Connecticut  Agricultural  Experiment 

Station,  Nezv  Haven. 

Every  grower  is  familiar  with  the  fact  that  no  two  tobacco 
plants  are  alike.  Frequentl}^  the  grower  finds  a  plant  in  the 
field  that  almost  or  quite  fulfils  his  ideal  of  a  perfect  plant.  It 
would  be  very  desirable  to  produce  uniform  crops  of  the  type 
of  these  best  plants,  because  they  would  be  much  more  pro- 
ductive and  of  better  quality.  As  a  result  of  the  investigations 
which  have  been  carried  on  in  the  Connecticut  valley  and  else- 
where, it  has  been  found  that  it  is  possible  for  every  grower  to 
select  the  type  of  plant  he  desires  to  grow  as  seed  plants,  and 
by  protecting  the  flowxrs  produced  by  these  plants  from  cross- 
fertilization,  to  secure  uniform  types  or  strains  like  the  parent 
seed  plants.  This  important  improvement  can  be  made  by  the 
grower  in  a  simple  and  practical  manner,  as  described  in  the 
following  article,  without  any  extra  expense  and  with  very  little 
trouble  or  work.  In  view  of  the  fact  that  any  improvement  in 
the  3deld  or  quality  of  the  crop  secured  by  seed  selection  is  pure 
profit,  because  it  costs  no  more  to  grow  good  plants  than  poor 
ones,  there  is  no  farmer  who  can  afford  to  grow  a  poor  type 
of  tobacco  when  it  is  possible  to  produce  improved  strains. 

Possibility  of  Improving  the  Quality  of  Tobacco. 

There  is  no  lack  of  either  practical  experience  or  experimental 
evidence  to  prove  that  improved  strains  of  tobacco  may  be  pro- 
duced by  systematic  seed  selection  and  breeding.  In  the  Con- 
necticut valley  there  are  many  strains  of  the  broadleaf  or  seed 
leaf  variety,  which  are  adapted  to  certain  market  require- 
ments, or  local  soil  and  climatic  conditions.  The  broadleaf 
variety  is  commonly  believed  to  have  been  produced  from 
the  Maryland  smoking  tobacco  variety,  the  seed  of  which 
was  brought  into  the  valley   over   a  half -century   ago.      The 


*  For  a  more  complete  discussion  see  Year  Book  U.  S.  Dept.  Agric.  1904. 


4  CONNECTICUT    EXPERIMENT   STATION,    BULLETIN    150. 

local  strains,  as  the  Halliday,  the  Willow  brook,  and  many 
others,  were  produced  by  certain  growers  who  selected  a  par- 
ticular type  of  seed  plant  that  suited  their  fancy  for  several 
years  in  the  usual  manner  until  the  type  became  fairly  uniform 
and  constant.  The  popular  Havana  seed  variety  is  reported  to 
have  been  produced  from  seed  originally  imported  from  Cuba, 
and  grown  in  Connecticut  for  a  number  of  years  in  small 
patches,  until  the  variety  had  become  adapted  to  the  soil  and 
climatic  conditions  of  this  section.  There  are  at  present  a 
number  of  strains  of  this  variety,  distinguished  by  peculiar 
shape  of  leaves  or  other  characteristics,  which  have  been  secured 
by  many  years  of  careful  seed  selection  by  the  growers.  One 
of  the  most  striking  illustrations  of  the  possibilities  of  seed 
selection  is  the  origin  of  the  White  Burley  variety.  This 
variety,  as  is  well  known,  was  produced  by  a  grower  in  southern 
Ohio,  who  noticed  in  his  field  of  Red  Burley  these  plants  having 
the  peculiarities  of  the  now  well-known  White  Burley  type,  and 
saved  them  for  seed.  From  this  beginning  a  great  industry 
has  been  developed  in  southern  Ohio,  in  Kentucky  and  other 
states.  Numberless  other  illustrations  might  be  cited  in  this 
connection,  but  on  account  of  the  fact  that  they  are  well  known 
to  almost  every  grower,  and  are  matters  of  history,  it  is 
unnecessary  to  further  comment  on  the  work  that  has  been 
done,  in  order  to  prove  the  fact  that  it  is  possible  to  greatly 
modify  and  improve  this  crop  by  an  application  of  the  laws  of 
plant  breeding. 

In  the  season  of  1903  the  writer  began  a  series  of  experiments 
in  the  Connecticut  valley  with  tobacco  in  order  to  determine 
the  possibilities  of  improvement  by  the  application  of  the  laws 
of  plant  breeding,  as  worked  out  in  the  cases  of  corn,  cotton 
and  other  farm  crops,  and  to  find  the  methods  by  which  this 
improvement  could  most  rapidly  be  effected.  It  is  not  oppor- 
tune in  this  short  bulletin  to  go  into  details  as  to  the  results 
of  the  experiments  in  that  and  the  succeeding  season,  which 
will  be  presented  in  a  later  and  more  extended  bulletin,  but  the 
general  results  will  be  briefly  discussed  here  and  the  practical 
results  and  methods  presented  for  the  help  of  the  growers  for 
this  season.  This  matter  is  not  theoretical  or  impractical  and 
of  scientific  interest  only,  but  it  is  intensely  practical  and  can 
be  applied  by  every  grower  of  tobacco  to  the  advantage  of  his 
crop,  and  with  increased  profits  in  his  business. 


IMPROVEMENT    OF    TOBACCO   BY    BREEDING.  5 

Lack  of  Uniformity  of  Plants  in  the  Average  Tobacco  Crop. 

The  extent  of  the  variation  or  lack  of  uniformity  among 
plants  in  fields  of  tobacco  in  the  Connecticut  valley  is  best  illus- 
trated in  the  crops  grown  from  seed  originally  imported  from 
Sumatra  and  Cuba,  but  grown  in  Connecticut  for  several  years. 
In  a  careful  and  systematic  study  of  such  crops  by  the  writer, 
it  was  found  that  the  difference  in  plants  was  so  great  that  it 
was  possible  to  separate  out  and  classify  several  distinct  types. 
The  differences  between  these  types  were  just  as  marked  as  the 
distinguishing  characteristics  of  the  broadleaf  and  the  Havana 
seed  varieties.  These  variations  were  not  due  to  local  soil  or 
fertilizer  conditions,  as  generally  supposed,  but  to  the  seed,  as 
shown  by  the  fact  that  they  occurred  in  all  parts  of  the  fields 
'investigated,  in  many  cases  two  plants  of  radically  different 
types  growing  side  by  side  under  as'nearly  uniform  conditions 
as  is  ever  secured.  The  type  characteristics  were  very  marked, 
and  easily  distinguished,  even  by  the  most  casual  observer. 
Some  of  these  are  shown  in  Plate  I.  In  one  of  the  types 
of  Connecticut  Sumatra  the  leaf  was  very  long,  narrow, 
heavy,  with  peculiar  angular  veins,  unusual  light  greenish 
gray  color,  and  of  very  peculiar  and  characteristic  habit  of 
growth.  From  its  fancied  resemblance  to  the  so-called  Bel- 
gian tobacco,  it  was  called  and  is  recorded  as  the  Belgian 
type.  Another  of  the  types  produced  nicely  rounded  leaves, 
from  eighteen  to  thirty  on  every  plant,  with  very  peculiar  wavy 
or  crumpled  edges,  comparable  in  many  ways  to  the  crumpled 
leaves  of  some  varieties  of  lettuce.  The  leaves  of  this  type 
were  very  thin  and  in  most  cases  lacked  strength  and  elasticity, 
so  that  when  wrapped  on  cigars  a  considerable  percentage  was 
likely  to  break  or  be  injured  in  some  manner.  From  the  char- 
acteristic wavy  margin  of  the  leaves,  these  plants  of  tobacco 
were  classified  as  the  crumpled  type.  Another  type  found  in 
these  crops,  called  the  Sumatra,  produced  leaves  that  were  nearly 
round  and  were  borne  in  a  drooping  position  on  the  stalks. 
This  type  of  leaf  in  the  field  was  pronounced  by  one  of  the 
extensive  growers  as  ideal  for  cigar  wrapper  purposes,  so  far 
as  the  shape  of  leaf  and  other  qualities  that  can  be  determined 
in  the  field  were  concerned.  The  leaves  had  good  body,  and 
extremely  regular  and  fine  veins,  which  stood  out  almost  at 
right  angles  with  the  mid  ribs.     One  of  the  most  striking  types 


6  CONNECTICUT    EXPERIMENT    STATION,    BULLETIN    I50. 

produced  very  large  leaves,  in  many  cases  larger  than  the 
largest  strains  of  the  broadleaf  variety,  and  a  characteris- 
tically large  number  of  them.  While  the  growth  of  the 
plants  was  very  slow  in  the  first  part  of  the  season,  they 
produced  ripe  tobacco  as  soon  as  the  early  maturing  types. 
The  rate  of  growth  of  the  plants  of  this  type  in  twenty- 
four  hours,  at  the  middle  of  .the  season,  was  nearly  double 
that  of  corn  at  the  most  favorable  time  for  rapid  growth. 
Another  type  produced  characteristically  small  leaves,  called  the 
greenleaf  type,  because  of  the  deep  shade  of  green  color  of  the 
leaves.  The  average  length  of  the  leaves  of  this  type  was  not 
more  than  one-quarter  the  average  length  of  the  leaves  of  the 
broadleaf  type.  The  leaves  were  very  uniform  in  size  as  well 
as  shape  from  the  top  to  the  bottom  of  the  plants.  The  number 
of  leaves  per  plant  was  very  large,  in  many  cases  plants  pro- 
ducing forty  desirable  leaves.  'This  increase  in  number  of  leaves 
in  this  type  was  not  accompanied  by  a  corresponding  increase 
in  the  height  of  the  plants,  but  was  correlated  with  short  inter- 
nodes  or  spaces  between  the  leaves  on  the  stalk. 

In  all  of  the  crops  grown  from  freshly  imported  seed,  there 
appeared  a  large  proportion  of  abnormally  early,  small,  heavy 
leaved  types,  commonly  called  freaks.  These  plants  had  in 
most  cases  the  branching  habit  of  the  wild  or  unimproved 
varieties  of  tobacco,  and  for  this  and  other  well-founded 
reasons  were  supposed  to  be  reversions  to  some  of  the  unim- 
proved varieties  from  which  the  present  varieties  have  been 
developed.  These  freaks  were  particularly  noticeable  in  the 
crops  grown  from  freshly  imported  Cuban  seed.  In  one  typical 
field  of  this  kind,  the  writer  found  about  thirty-three  per  cent, 
of  the  plants  to  be  of  this  freak  type.  The  irregular  stand  can 
be  seen  in  Plate  II,  prepared  from  a  photograph  of  this 
field.  Inasmuch  as  the  leaves  produced  by  the  freak  plants 
are  almost  wholly  worthless  for  wrapper  purposes,  it  can  readily 
be  seen  that  such  crops  are  not  profitable  to  the  growers. 
After  a  most  careful  study  of  this  subject  it  can  be  safely 
said  that  in  no  case  should  growers  depend  on  freshly  imported 
seed  for  their  main  crops  of  tobacco.  If  it  is  desirable 
for  the  grower  to  test  foreign,  imported  or  new  seed  of  any 
kind,  it  should  be  done  on  a  small  scale  until  it  is  determined 
that  the  variety  is  adapted  to  local  soil  and  climatic  conditions. 


IMPROVEMENT    OF    TOBACCO   BY    BREEDING.  /, 

or  acclimated  strains  are  produced  by  seed  selection  and 
breeding. 

The  variation  in  type  in  the  broadleaf,  Havana  seed  and 
other  so-called  native  varieties  is  not  so  marked  as  in  the  case  of 
varieties  grown  from  recently  imported  seed.  The  individual 
variation  or  differences  between  different  plants  as  regards  the 
number,  shape,  and  size  of  leaves,  the  number  of  suckers,  the 
number  of  seed  pods  and  other  characters  are  nearly  as 
great  as  among  plants  grown  from  imported  seed.  In 
every  field  examined  some  plants  were  found  with  nearly 
double  the  number  of  leaves  found  on  the  average  plants 
in  the  field.  Many  plants  produce  rounded  leaves,  while  others 
bear  long,  narrow  and  pointed  leaves.  Some  plants  have  a 
large  number  of  suckers,  while  others  have  comparatively  few 
of  them.  Some  plants  produce  from  one  hundred  and  fifty  to 
two  hundred  seed  pods,  while  others  bear  from  twenty-five  to 
one  hundred  pods.  In  many  instances  the  writer  has  found 
plants  that  produce  ripened  leaves  two  weeks  earlier  than  the 
remainder  of  the  crop.  Many  plants  produce  leaves  that  ripen 
uniformly  from  the  top  to  the  bottom  of  the  plants,  while  others 
produce  bottom  leaves  and  lower  leaves  that  ripen  from  ten  days 
to  two  weeks  before  the  upper  or  top  leaves  are  ready  to  harvest. 
Some  plants  produce  leaves  with  large  and  coarse  veins,  while 
others  in  the  same  field  bear  leaves  with  fine  and  small  veins. 
Individual  plants  were  found  in  all  fields  bearing  leaves  having 
more  desirable  body,  stretch  or  elasticity,  color  or  appearance, 
and  other  characteristics,  than  the  other  plants  in  the  same  field. 
In  fact  the  tobacco  crops  present  the  greatest  amount  of  vari- 
ation in  type  and  individual  characteristics  of  any  farm  crop 
known  to  the  writer.  The  large  number  of  grades  of  color, 
sizes,  and  qualities  of  leaves,  which  the  growers  find  necessary 
to  assort  after  the  tobacco  is  cured  or  fermented,  is  definite 
evidence  of  the  lack  of  uniformity  in  this  crop.  This  lack  of 
uniformity  in  the  crop  is  detrimental  to  its  value,  not  only 
because  some  of  the  grades  are  poor  and  of  very  little  value, 
but  also  on  account  of  the  cost  of  assorting  these  variations  into 
their  respective  grades. 

Increase  in  the  uniformity  of  the  tobacco  crop  means 
increased  yield   and   a  more  valuable   crop.      Inasmuch   as   it 


8  CONNECTICUT    EXPERIMENT   STATION,    BULLETIN    I50. 

costs  as  much,  if  not  more,  to  grow  a  crop  lacking  in  uni- 
formity, as  to  grow  a  uniform  crop  of  desirable  plants,  this 
increase  in  value  is  pure  profit  to  the  grower.  The  methods 
of  seed  selection  and  breeding  presented  in  this  bulletin  have 
been  found  both  experimentally  and  in  farm  practice  to  pro- 
duce more  uniform  crops  of  tobacco,  with  no  extra  expense  to 
the  grower. 

Self -Fertilization  and  Cross-Fertilisation  of  Tobacco. 

In  order  to  present  the  methods  of  seed  selection  and  breed- 
ing, it  is  necessary  to  refer  to  the  tobacco  flowers  and  the 
natural  method  of  fertilization  in  tobacco  plants.  The  appear- 
ance and  structure  of  the  flower  may  be  seen  in  Plates 
III  and  VI.  The  tobacco  flower  consists  of  a  brightly  col- 
ored tube-like  corolla,  enclosing  five,  more  or  less,  stamens, 
i.  e.,  slender  filam.ents  bearing  at  their  ends  plump  bodies, 
called  anthers,  in  shape  somewhat  resembling  a  cigar.  When 
the  flower  is  just  about  to  open,  these  anthers  contain  a  large 
amount  of  fine  dust-like  particles,  the  pollen  grains,  or  the  male 
fertilizing  element  of  the  flower.  At  the  base  of  the  flower  is 
a  small  pod-like  receptacle,  which  later  forms  the  seed  pod  and 
which  bears  a  long,  slender,  rod-like  projection,  having  a  knob- 
like swelling  at  the  tip,  the  whole  being  called  the  pistil.  This 
knob-like  portion  is  the  receptive  part  of  the  female  portion, 
or  stigma  of  the  flower,  on  which  the  pollen  falls  which  ferti- 
lizes the  flower.  In  the  early  stage  of  the  development  of  the 
flower,  this  stigma  projects  above  the  cluster  of  anthers,  but 
later  the  anthers  gradually  grow  past  it,  at  the  same  time 
opening  and  discharging  the  pollen  so  that  it  falls  on  and 
fertilizes  the  stigma.  At  this  time  the  stigma  will  be  found  to 
be  covered  with  a  sticky  substance  to  which  the  pollen  adheres. 
Gradually  the  anthers  push  out  of  the  opened  flower  and  pro- 
ject beyond  the  stigma.  The  different  stages  in  the  develop- 
ment of  the.  flower  and  seed  are  shown  in  Plate  VI.  At  the 
base  of  the  tube-like  corolla  will  be  found  a  secretion  of 
sweetish  honey-like  substance,  which  can  be  shaken  out  of  the 
flowers  and  falls  like  drops  of  rain  on  the  plant.  Many  species 
of  bees  and  other  small  insects  crawl  down  into  the  opened 
flowers  and  feed  upon  this  honey-like  substance.  The  writer  has 
observed  humming  birds  feeding  on  this  honey,  similar  to  the 


IMPROVEMENT   OF   TOBACCO   BY    BREEDING.  9 

manner  in  which  they  visit  the  fiov^ers  of  the  common  honey- 
suckle. In  passing  to  and  from  these  flowers,  they  naturally 
carry  the  pollen  from  flower  to  flower,  and  from  plant  to  plant 
and  rub  it  off  on  the  stigmas,  and  in  this  way  effect  "cross- 
fertilization"  among  the  plants  in  the  field.  Cross-fertilization 
must  be  very  general  among  tobacco  seed  plants  in  the  field 
under  the  ordinary  conditions. 

A  flower  is  "self-fertilized"  when  the  seeds  are  produced  by 
the  impregnation  or  fertilization  of  its  pistil  by  pollen  from  its 
own  stamens.  It  is  "cross-fertilized"  when  seeds  are  produced' 
by  impregnation  with  pollen  from  another  plant.  In  some 
species  of  plants  cross-fertilization  is  absolutely  essential  to  seed 
production.  In  other  species  it  produces  more  and  better  seed 
than  self-fertilization.  But  tobacco  belongs  to  still  another 
class  of  plants  which  are  abundantly  self-fertile  and  in  which 
self-fertilization  is  apparently  more  effective  for  seed  pro- 
duction than  cross-fertilization. 

Charles  Darwin  found  in  greenhouse  experiments  that  "in 
six  trials  with  crossed  and  self-fertilized"  (tobacco)  "plants, 
belonging  to  three  successive  generations,  in  one  alone  did  the 
crossed  show  any  marked  superiority  in  height  over  the  self- 
fertilized ;  in  four  of  the  trials  they  were  approximately  equal ; 
and  in  one  (i.  e.  in  the  first  generation)  the  self-fertilized  plants 
were  greatly  superior  to  the  crossed.  In  no  case  ■  did  the  cap- 
sules from  flowers  fertilized  with  pollen  from  a  distinct  plant 
yield  many  more  and  sometimes  they  yielded  much  fewer  seeds 
than  the  capsules  from  self-fertilized  flowers." 

Advantages  of  Using  Seed  from  Self -Fertilised  Flozvers. 

In  the  last  two  years,  extensive  experiments  have  been  made 
in  the  Connecticut  valley  on  the  relative  value  of  seed  produced 
by  exclusive  self-fertilization  and  of  seed  produced  by  natural 
cross- fertilization.  These  experiments  have  been  made  with 
the  Connecticut  Havana,  Broadleaf,  Sumatra  and  Cuban  types 
of  tobacco,  under  cloth  and  in  the  open,  and  on  a  commercial 
scale;  in  all  cases  with  like  results.  These  results  we  consider 
are  of  the  very  greatest  importance  to  growers  and  are  here 
very  briefly  summarized. 

Seed  produced  by  exclusive  self-fertilization  for  the  two 
generations   covered  by   our  observations  has   been   lighter   in 


lO         CONNECTICUT    EXPERIMENT   STATION,    BULLETIN    I50, 

color,  heavier,  freer  from  mold  or  fungous  disease,  and  in  all 
ways  more  valuable,  as  will  appear  in  what  follows. 

The  plants  grown  from  self-fertilized  seed  reproduced  exactly 
the  character  of  the  mother  plant  from  which  they  came.  If 
the  parent  had  large  leaves,  so  did  all  the  progeny.  If  the 
parent  had  small  leaves,  so  did  all  the  progeny;  and  in  both 
cases  the  average  size  was  the  same  as  the  average  size  of  the 
parent's  leaves.  This  uniformity  and  exact  reproduction  of 
the  characters  of  the  mother  plant  are  well  shown  in  Plate  IV. 
Figure  A  shows  two  rows  of  plants  from  the  self-fertilized 
seed  of  a  single  mother  plant.  The  uniformity  in  size  of  the 
plants  as  well  in  the  shape,  size,  veining  and  number  of  leaves 
is  very  striking.  The  adjoining  rows  of  tobacco  are  of  a  differ- 
ent type.  Figure  B,  on  the  same  plate,  shows  a  like  uniformity 
in  two  rows  of  plants  from  seed  of  a  single  mother  plant  of  the 
so-called  Belgian  type. 

Plants  from  a  parent  with  few  suckers  had  correspondingly 
few  suckers.  The  shape  of  the  leaves  of  the  offspring  was 
closely  like  the  shape  of  the  parent's  leaves. 

The  same  correspondence  appeared  in  the  number  of  leaves. 
If  the  parent  had  thirty-five  leaves,  the  offspring  averaged 
about  thirty-five  leaves.  If  the  parent  bore  ten,  the  offspring 
averaged  ten. 

In  a  word,  the  individual  characters,  such  as  shape  and  color 
of  leaves,  numbers  of  leaves  and  suckers,  body  or  texture,  size 
of  veins,  time  of  maturity,  and  all  other  observed  characters 
were  transmitted  from  the  parent  seed  plants  to  their  offspring 
with  marvelous  uniformity. 

Two  particular  experiments  emphasize  this  accurate  trans- 
mission of  individual  characters  by  the  seed  of  self-fertilized 
flowers. 

In  a  field  of  Connecticut  Sumatra,  several  hundred  parent 
plants  of  different  types  were  selected  and  the  seed  saved 
under  bag;  hence  it  was  exclusively  from  self-fertilization. 
The  progeny  of  these  plants  were  set  out  in  separate  rows  in 
the  same  field,  under  as  uniform  conditions  as  it  is  possible 
to  secure,  the  following  season.  One  of  these  types  produced 
leaves  which  would  not  burn,  even  with  all  of  the  tests  that 
were  applied.  Growing  side  by  side  with  this  type,  in  several 
parts  of  the  field,  was  another  type,  which,  tested  in  the  same 


IMPROVEMENT    OF    TOBACCO   BY    BREEDING.  II 

ways,  had  the  most  perfect  burn  of  any  kind  of  tobacco  grown 
in  any  part  of  the  world.  Here  were  two  types,  from  the  same 
original  lot  of  seed,  the  parents  grown  in  the  same  field,  the 
progeny  grown  under  as  uniform  condition  as  is  ever  secured 
in  the  field,  the  tobacco  cured  and  fermented  absolutely  alike, 
one  of  which  would  not  burn,  and  the  other  burned  perfectly. 

One  more  instance  is  presented  because  of  its  specially  inter- 
esting nature  and  importance.  A  field  was  set  out  with  plants 
grown  from  imported  seed,  which  were  attacked  by  a  fungous 
root  disease,  and  all  died  with  the  exception  of  a  few 
plants.  These  resistant  or  immune  plants  were  found  irregu- 
larly over  the  field,  and  produced  ripe  tobacco  of  excellent 
quality.  All  the  other  plants  were  completely  destroyed  with 
the  exception  of  one  or  two  semi-resistant  plants  that  produced 
a  large  amount  of  seed,  but  very  few  and  extremely  small 
leaves.  The  seed  was  saved  separately  from  the  resistant 
and  semi-resistant  plants,  and  sowed  in  separate  sections  of 
the  seed  beds.  The  resistant  seed  produced  perfectly  resistant 
plants,  both  in  the  seed  bed,  and  in  the  field  where  the  plants 
were  destroyed  the  previous  year.  These  are  shown  in  Plate 
V.  Most  of  the  seedlings  from  the  semi-resistant  seed  died 
in  the  seed  bed,  but  enough  were  finally  secured  to  set  out  one 
or  two  rows  in  the  field.  These  plants  grew  slowly,  some  died, 
and  none  reached  maturity,  all  having  the  characteristics  of 
the  diseased  plants  in  root,  stalk  and  leaves.  Some  of  the 
resistant  seed  was  sowed  on  the  seed  beds  where  the  diseased 
seedlings  had  been  destroyed  by  the  disease,  and  this  immune 
seed  produced  perfectly  resistant  plants  under  these  circum- 
stances. 

These  extensive  observations  and  experiments  show  that  the 
transmitting  power,  as  defined  by  Dr.  H.  J.  Webber,  or  the 
"prepotency"  of  the  seed  of  tobacco  from  self-fertilized  flowers 
is  wonderful,  and  we  believe  of  very  great  practical  importance. 
With  an  understanding  of  its  value,  with  keen  observation  of 
the  characters  of  individual  tobacco  plants  which  it  is  desirable 
to  retain  and  reproduce,  and  with  very  little  labor,  the  grower 
can  modify,  change  and  improve  his  strain  of  tobacco  and  can 
produce  crops  which  are  uniform  in  all  respects  and  like  the 
parent  plants  which  he  selects  for  self-fertilized  seed  production. 


12         CONNECTICUT   EXPERIMENT   STATION,    BULLETIN    I50. 

Method  of  Selecting  Plants  and  Securing  Self -Fertilisation. 

We  may  now  briefly  describe  how  this  is  to  be  done.  In  the 
first  place,  the  field  from  which  the  selections  of  seed  plants  are 
to  be  made  should  be  gone  over  carefully,  before  the  plants  are 
topped,  and  the  plants  which  come  nearest  the  ideal  of  the 
grower  should  be  selected  for  seed  plants.  This  selection  can 
be  made  at  any  time  before  topping,  during  the  cultivation  of 
the  field  as  well  as  by  special  visits  for  this  purpose,  and  during 
the  topping  process.  The  grower  should,  at  these  times,  carry 
a  handful  of  tags  in  his  pocket  and  tie  one  on  each  of  the 
plants  which  suits  his  fancy.  No  good  selections  are  ever  made, 
or  permanent  progress  accomplished,  by  hit  or  miss  and  careless 
methods.  The  seed  heads  of  the  selected  seed  plants  must  be 
covered  before  any  of  the  flowers  open  in  order  to  prevent  any 
possible  cross-fertilization.  If,  by  accident,  some  flowers  have 
opened  before  the  seed  heads  are  bagged,  they  should  be  care- 
fully picked  off  and  thrown  away.  It  is  a  good  plan  to  pick  off 
all  of  the  top  leaves  down  to  where  the  plant  would  have  been 
topped  if  it  had  not  been  saved  for  seed.  All  of  the  large  lower 
seed  branches  should  be  broken  off,  and  only  the  central  cluster 
of  seed-bearing  branches  left  for  seed  purposes.  As  a  rule, 
each  mature  pod  contains  from  three  to  seven  thousand  seed, 
so  it  can  be  readily  seen  that  a  few  pods  will  produce  a  large 
amount  of  seed.  Of  course,  the  grower  should  save  many 
times  the  amount  of  seed  that  he  expects  to  use. 

The  common  manila  twelve-pound  grocery  bag,  procurable 
at  any  good  grocery,  hardware,  or  general  store,  is  admirably 
suited  for  this  purpose.  The  bag  with  a  roof-shaped  bottom 
is  better  than  the  square-bottom  shape  because  it  sheds  the  rain 
better.  The  bag  should  be  carefully  fitted  over  the  seed  head, 
and  the  open  end  tied  around  the  stalk  below  the  seed  head,  not 
so  tightly  as  to  injure  the  plant,  or  so  loosely  as  to  allow  the 
bag  to  be  slipped  or  blown  off  by  the  wind,  or  allow  the  visits 
of  insects  which  might  crawl  up  the  stem  inside  the  bag.  The 
adjustment  of  the  bag  is  shown  in  Plate  VII. 

As  the  plant  grows  in  height,  the  bag  should  be  moved  up 
the  plant  so  as  to  accommodate  the  extra  growth  and  prevent 
the  seed  head  from  pressing  against  the  bottom  of  the  bag,  which 
might  injure  or  break  off  the  flowers  and  seed  pods.  Late  in 
the  season,  after  all  or  most  of  the  pods  have  set,  the  bags 


IMPROVEMENT    OF    TOBACCO   BY    BREEDING.  1 3 

should  be  opened  and  all  of  the  loose  flowers  and  other  debris 
shaken  out,  after  which  it  should  be  immediately  retied  and 
allowed  to  remain  in  this  condition  until  the  pods  have  turned 
brown,  indicating  maturity.  Some  growers  advocate  picking 
off  the  leaves  from  the  seed  plants  as  they  ripen,  while  others 
allow  them  to  remain  until  the  seed  heads  are  harvested.  If 
the  suckers  are  carefully  kept  removed,  it  will  be  perfectly  safe 
to  allow  the  leaves  to  remain  on  the  seed  plants.  On  the  other 
hand,  if  it  is  desirable  to  save  the  leaves,  they  can  be  picked  off 
as  they  ripen  without  injury  to  the  seed. 

We  would  advise  those  who  wish  to  make  the  most  careful 
selection  and  who  have  the  facilities  for  it,  to  pick  the  leaves 
from  the  separate  seed  plants,  when  they  are  ripe,  cure  them  as 
usual  in  the  barn  with  the  rest  of  the  crop,  keeping  the  leaves 
of  each  plant  by  themselves,  suitably  labeled.  If  opportunity 
offers,  let  them  be  fermented  with  other  tobacco  during  the 
winter.  They  can  then  be  judged  quite  fairly  as  to  burn,  colors 
and  texture,  and  the  seed  of  the  very  best  of  them  saved  for 
the  following  crops. 

When  the  pods  are  mature,  the  seed  heads,  bags  and  all, 
should  be  cut  off,  and  hung  up  in  a  dry,  airy  place,  where 
they  can  thoroughly  dry  out  with  a  free  circulation  of  air. 
After  drying  it  is  a  good  plan  to  keep  them  where  the  tempera- 
ture does  not  fall  much  below  zero.  'In  the  spring,  when  the 
time  comes  for  the  preparation  of  the  seed  for  sowing,  the 
largest  and  best  pods  should  be  picked  off  by  hand,  and  thor- 
oughly threshed  out  to  remove  all  seed.  The  seed  should  then 
be  separated  with  the  seed  separator  in  the  way  described  in 
Bulletin  149  of  this  Station. 


PLATE  I. 


Differences  in  characters  of  leaves  from  plants  of  the  same  variety  of  tobacco. 

PLATE  IL 


Tobacco  grown  in  Connecticut  from  Seed  just  imported  from  Cuba,   showing 
freak  plants  and  irregular  stand. 


PLATE  III. 


A  Flower-Head  of  Tobacco  read}'  to  cover.     The  opened  flowers  show  position 
of  anthers  and  stiemas  at  time  of  fertilization. 


PLATE  IV. 


Fig.  A.      Uniformit}-  in  Tobacco  Plants  from  Self-fertilized  Seed.     The  two  central 
rows  of  one  strain  ;  adjoining  rows  frotn  a  different  strain  of  same  variety. 


Fig.  B.      Uniformity  in  Tobacco  Plants  from   Self-fertilized  Seed  of  Belgian  type. 


PLATE  V. 


Resistant  and  semi-resistant  Plants  growing  on  infected  Soil. 

PLATE  VL 


Different  stages  in  the  Development  of  the  Tobacco  Flower  and  Seed. 


PLATE  VII. 


Flower  Head  protected  from  foreign   pollen  ("cross-fertilization"),   by  a 

manila  bag. 


I 


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